Main doors are known for closing garages or the like having a leaf composed of one or more panels moving along guides.
In the case of a single-panel leaf, the leaf has height and width dimensions equal to the entire access opening.
In the case of the leaf being composed of a plurality of panels, instead, the latter have a substantially rectangular shape, with width equal to the width of the access opening to the compartment, and are articulated with one another in various ways.
A particular example of a main door with the panels articulated to one another is shown in the patent document WO 2012/117277.
To open the leaf, devices are known including a reversible motor which commands an operating shaft which transmits movement to a pair of pulleys arranged alongside the leaf and designed to retransmit a respective cable loaded with a counterweight.
The pulleys therefore act both as supports for the counterweights and as parts for moving the leaf.
Due to the pressure differences between the inside of the compartment to be closed and the outside, differences mostly created by the fact that the compartment is closed or open, but exposed to air currents contrary to the direction of closing movement of the leaf, it often occurs that the leaf does not correctly come alongside the garage compartment walls or violently collides with the fixed frame.
The risk therefore exists of the main door remaining partially open or of it producing undesired noises and vibrations which over time can loosen the adherence of the frame fixed to the masonry.
Because these causes are to some extent tied to particular environmental conditions, it is extremely difficult, if not impossible without incurring heavy maintenance costs, to adequately adjust or permanently fine tune the main door.
To at least partially overcome the above drawbacks, the patent document IT 229412 teaches to use a transmission and distribution unit of the motor motion and a winding-unwinding device linked with the transmission and distribution unit.
The winding-unwinding device has a belt or a cable fastened to the top of the leaf, so that during leaf opening, the belt or the cable unwinds and during closing it passively rewinds, while in the final juxtaposition section, the winding-unwinding device starts up and drags the leaf to abut against the fixed structure.
The transmission and distribution unit consists of a mechanism with feelers, gear wheels, and conical and helical couplings which transfer the movement from the motor to the pair of pulleys during the leaf opening and closing phase, and to the winding-unwinding device during the final closing phase.
Such transmission and distribution unit is however considerably complicated from a mechanical-structural viewpoint and difficult to make, assemble and install, with consequent increase in total production costs which inevitably increase the retail price, with the risk of making the product less attractive for consumers.